1. Field of the Invention
The present invention relates to a process for forming a mask pattern and a process for producing a thin film magnetic head.
2. Description of the Related Art
Along with the development of a hard disk unit having a small size and a large capacity in recent years, a demand for a small-sized hard disk unit, such as a 2.5-inch type, is increased particularly in a field where an application to a portable personal computer is contemplated.
A magnetoresistance effect magnetic head (hereinafter referred to as an MR head), in which a change in resistance of a magnetic film having a magnetoresistance effect (hereinafter referred to as an MR film), the resistivity of which is changed depending on a magnetic field, is detected as a reproduced output voltage, receives attention as a magnetic head realizing a large capacity in a small-sized hard disk unit because it has such characteristics that a high reproduced output level can be obtained with a low media velocity.
The MR head is produced, for example, in such a manner that an MR film, an electrode film, an insulating film and the like are formed on a non-magnetic substrate by a thin film process, and these films are etched to a desired shape by a photolithography process.
For example, in the case where a magnetoresistance effect device (hereinafter referred to as an MR device) is produced, a thin film for an MR device comprising an MR thin film is formed on a surface on which the MR device is to be formed. A resist is then coated on the thin film for an MR device. Exposure to light and development are conducted for the resist to form a resist pattern having a desired shape. Specifically, the resist pattern has such a pattern in that the resist remains in a part to be the MR device. Etching is then conducted by using the resist pattern as a mask to remove the thin film for an MR device exposed from the mask. The etching is conducted, for example, by ion etching. Finally, the resist is removed to obtain a state in that the MR device is formed at the prescribed position.
When the MR film exposed from the mask is removed by etching using the resist pattern as the mask, a problem arises in that the thin film for an MR device removed by etching is re-attached to the side surface of the resist.
When the MR film removed by etching is re-attached to the resist, the attached MR film forms burr on the side surface of the MR film on removal of the resist. The formation of burr not only greatly lowers the sensitivity of the MR device but also becomes a reason of deterioration of a yield of the MR head.
The burr has been mechanically removed by scraping the surface of the MR device with a brush and washing with water. However, the surface of the MR device is damaged by this method. Furthermore, another problem arises in that the MR device is deteriorated by water used for washing.
In order to suppress the re-attachment of removed matters by etching and the formation of the burr due to the re-attached matters, improvement of a cross sectional shape of the mask patterns has been proposed, but a satisfactory effect has not been obtained.